Facebook users in the United Kingdom were unable to access the social networking site for two hours, as it suffered a major blackout across Europe.

"Today, we experienced technical difficulties causing the site to be unavailable for a number of users in Europe. The issue has been resolved and everyone should now have access to Facebook. We apologize for any inconvenience," The Telegraph quoted a Facebook spokesperson, as saying.

The firm blamed the blackout affecting users in France, Germany, Russia and South Africa, on "technical problems", but did not divulge details. Third parties however, suspect that a temporary problem with Facebook's European DNS servers might have led to the blackout.

Servers are responsible for connecting the address "Facebook.com" with the actual content of the website, but attempts to contact them as normal had received no response during the blackout. A Belgian government agency for responding to hacking, CERT.be claimed on Twitter that the Distributed Denial of Service attack had led to the blackout but it could not immediately be confirmed.

In a DDoS attack, hackers deliberately render servers inaccessible by overloading them with traffic.